Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque;h,w=map(int,input().split());m=[input()for _ in[0]*h];v=[[-1]*w for _ in[0]*h];q=deque([[0,0]]);v[0][0]=0;c=sum(t.count('#')for t in m)
while q:
 y,x=q.popleft()
 for i,j in([1,0],[-1,0],[0,1],[0,-1]):
  t,u=y+i,x+j
  if t+1and t<h and u+1and u<w and m[t][u]=='.'and v[t][u]<0:v[t][u]=v[y][x]+1;q.append([t,u])
print(-1*(v[h-1][w-1]<0)or h*w-c-v[h-1][w-1]-1)